The prologue, currently showing before select 70mm IMAX showings of Mission: Impossible - Ghost Protocol, serves as an action-heavy introduction to the mysterious and definitely menacing Bane.  While reaction to the clip has generally been quite positive, Bane's relative incomprehensibility has been a much-discussed issue since the prologue was first exhibited. 

Bane's one line in the new trailer allowed everybody to get in on the complaint, reportedly prompting concern at the studio over "The Bane Problem."  Before showing the footage publicly, Nolan mentioned that the audio mix was indeed final, and that it wasn't terribly important that audiences understand each and every line.  Undaunted by concerns at Warner Bros, Nolan apparently maintained that he wouldn't be changing Hardy's voice substantially.

Now, a source informs Collider that the studio sent out new audio accompaniment for the prologue several days ago.  This new mix, it seems, does not actually change Bane's voice at all, but lowers some background noises to make him more understandable.  The source explains,

“A friend of mine who is an IMAX projectionist told me they received a new soundtrack for the Dark Knight Rises prologue. He said it’s now a combo soundtrack with Mission: Impossible – Ghost Protocol, but the cool thing about this is that they’ve cleaned up the dialogue. They’ve gone in and lowered the background noise of the plane and other things, thus making Bane’s dialogue clearer and more understandable. He asked some people after they left the movie if they could understand Bane and they all said they had no issue understanding him, and were excited for the movie.”

That source adds that following Bane's diction is now easier by "40-50%, because he’s no longer being overpowered by the background noise that drowned him out before.”

Lest y'all think that this is just a rumor and Nolan wouldn't allow it, Collider also has photographic evidence that a new sound mix does exist and has been issued to IMAX theaters.  Here it is:

So based on what we've learned, Nolan is sticking to his guns and doing nothing to tweak Tom Hardy's work as Bane, but is cool with some rejiggering of the overall mix in order to help the audience out just a bit.  It remains to be seen if this will happen with the rest of the movie, but it seems a safe assumption.  Hardy's a new addition for the last chapter in Nolan's Bat-saga, along with fellow newcomers Anne Hathaway, Marion Cotillard, Joseph Gordon-Levitt, Juno Temple, Matthew Modine, and Josh Pence.  Christian Bale wears the pointy ears for the last time, while Gary Oldman, Michael Caine, and Morgan Freeman all have their last hurrah as well.

The Dark Knight Rises arrives in theaters on July 20, 2012.